Post Tropical Cyclone Helene: Dissipated Over Mexico

[tireman4]

Well, the GFS has been pretty good this year in as far as the tropics are concerned......

[sleetstorm]

It looks as though the Gulf of Mexico & Gulf Coast will see and get no tropical cyclone until that dome of high pressure vacates, huh?

[srainhoutx]

HPC Final Afternoon Update:

FINAL...

MADE ONLY COSMETIC CHANGES TO THE UPDATE PACKAGE FOR THE FINAL
ISSUANCE. THE 12Z/14 GFS AND GEFS MEAN HAVE TRENDED STRONGLY
TOWARD THE EUROPEAN CENTRE GUIDANCE AT THE END OF THE PERIOD...NOW
INDICATING PRIMACY OF THE LONGWAVE TROUGH OVER THE EAST.
COORDINATION WITH THE NATIONAL HURRICANE CENTER RESULTED IN THE
INTRODUCTION OF A SPOT TROPICAL LOW CREEPING UP THE ATLANTIC SIDE
OF THE MEXICAN COAST THROUGH MID PERIOD. EVEN IF NO ORGANIZED
SYSTEM DEVELOPS...THE TROPICAL FEED MAY WELL INTERSECT THE EDGE OF
THE WESTERLIES OVER SOUTHERN TEXAS...ENHANCING RAINFALL THERE.

[unome]

It looks as though the Gulf of Mexico & Gulf Coast will see and get no tropical cyclone until that dome of high pressure vacates, huh?

from HPC:

EXTENDED FORECAST DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
216 PM EDT TUE AUG 14 2012

VALID 12Z FRI AUG 17 2012 - 12Z TUE AUG 21 2012


PRELIMINARY UPDATE...

USED AN EVEN BLEND OF THE 00Z/14 DETERMINISTIC ECMWF AND ECENS
MEAN TO UPDATE THE PRELIMINARY FRONTS AND PRESSURES FOR DAYS 3
THROUGH 7. THE EUROPEAN CENTRE GUIDANCE HAS BE QUITE STABLE OVER
THE PAST FOUR CYCLES...AND SHARES MORE IN COMMON WITH THE 00Z/14
GEM GLOBAL AND UKMET THAN THE DETERMINISTIC GFS AND GEFS MEAN
DURING THE SECOND HALF OF THE PERIOD. THE FLOW AT THE MEDIUM RANGE
IS POSITIVE PNA...WITH THE POLAR FRONT MAKING IT ALL THE WAY TO
THE GULF STATES. THE GFS AND GEFS MEAN RAISE HEIGHTS OVER THE EAST
MORE RAPIDLY THAN THE OTHER GUIDANCE AFTER DAY 5...A BIAS OF THE
GFS.


FINAL...

MADE ONLY COSMETIC CHANGES TO THE UPDATE PACKAGE FOR THE FINAL
ISSUANCE. THE 12Z/14 GFS AND GEFS MEAN HAVE TRENDED STRONGLY
TOWARD THE EUROPEAN CENTRE GUIDANCE AT THE END OF THE PERIOD...NOW
INDICATING PRIMACY OF THE LONGWAVE TROUGH OVER THE EAST.
COORDINATION WITH THE NATIONAL HURRICANE CENTER RESULTED IN THE
INTRODUCTION OF A SPOT TROPICAL LOW CREEPING UP THE ATLANTIC SIDE
OF THE MEXICAN COAST THROUGH MID PERIOD. EVEN IF NO ORGANIZED
SYSTEM DEVELOPS...THE TROPICAL FEED MAY WELL INTERSECT THE EDGE OF
THE WESTERLIES OVER SOUTHERN TEXAS...ENHANCING RAINFALL THERE.


CISCO

[srainhoutx]

For what it's worth, the Euro has become a bit more bullish on a S Texas threat in the longer range...

[wxman57]

There is a big difference between the 12Z Euro and GFS. I'm looking at the Euro ensemble tracks for former TD 7 and about 95% of them are into the East Pac. Only 2 of the 50 or so of them enter the BoC. GFS develops an upper low over the SW Gulf, the Euro develops it along the west coast of Mexico.

[srainhoutx]

There is a big difference between the 12Z Euro and GFS. I'm looking at the Euro ensemble tracks for former TD 7 and about 95% of them are into the East Pac. Only 2 of the 50 or so of them enter the BoC. GFS develops an upper low over the SW Gulf, the Euro develops it along the west coast of Mexico.

Until the ECMWF can prove to me that it is actually doing a good job with the synoptic setup as well as actually have a clue this year, I'll tend to give more credence to the GFS. So far it has done rather well with the tropics. That said Corpus Christi offered an excellent discussion this afternoon and it is well worth the read...


.LONG TERM (THURSDAY THROUGH TUESDAY)...EARLY IN THE PERIOD HIGH
PRESSURE REMAINS IN CONTROL WITH HOT TEMPERATURES AND DRY CONDITIONS
CONTINUING. THE RIDGE WEAKENS FRIDAY INTO SATURDAY ALLOWING MOISTURE
TO INCREASE THROUGHOUT THE AREA. 700 MB TEMPS REMAIN PRETTY WARM
THROUGH FRIDAY AND WITH MOISTURE JUST BEGINNING TO STREAM IN THINK
CONVECTION WILL BE LIMITED SO HAVE BACKED OFF A BIT ON POPS IN THE
NORTHEAST ZONES. AT A MINIMUM...SHOULD SEE SEA BREEZE CONVECTION
RETURN FOR SAT/SUN PERIOD. ...AND THAT`S WHERE THINGS START TO GET
INTERESTING. PLENTY OF POTENTIAL SOLUTIONS FOR FORECAST LATE WEEKEND
INTO EARLY NEXT WEEK. NOT GOING TO SIDE ONE WAY OR THE OTHER AT THIS
POINT...WITH TOO MANY FACTORS THAT COULD CHANGE THINGS. THE GFS
MODEL HAS BEEN PERFORMING WELL FOR TROPICAL SYSTEMS SO FAR THIS
SEASON...SO CERTAINLY DON/T WANT TO ENTIRELY DISCOUNT IT. BUT THINK
TOO MANY THINGS HAVE TO HAPPEN PERFECTLY TO PUT TOO MUCH FAITH IN IT
AT THIS POINT. THE TROPICAL WAVE IN QUESTION IS THE REMNANT LOW OF
TD SEVEN...AND IS CURRENTLY EAST OF NICARAGUA. WITH A MORE SOUTHERLY
COMPONENT IN THE STEERING FLOW THE WAVE SHOULD MOVE NORTHWEST
SKIMMING HONDURAS/NICARAGUA...AND THEN LIKELY ACROSS THE YUCATAN
INTO THE GULF OF MEXICO. AT THAT POINT...STEERING AND SPEED WILL BE
BIG FACTORS IN DETERMINING WHAT HAPPENS NEXT. GFS IS ASSUMING A
SLOWER MOVEMENT ALLOWING THE WAVE...AND POSSIBLY CLOSED LOW TO GET
CAUGHT UP IN A TROUGH THAT IS PROGRESSING SOUTHWARD...BUT THEN
STRENGTHENS THE LOW ENOUGH TO BREAK OUT OF THE TROUGH AND CONTINUE A
WESTWARD PROGRESSION TOWARD THE TEXAS COAST. THINK THIS ALL LINING
UP PERFECTLY IS A STRETCH AT THIS POINT...BUT AGAIN...THE GFS HAS
BEEN DOING WELL. THE ECMWF ON THE OTHER HAND TAKES THE WAVE THROUGH
THE SOUTHWEST GULF OF MEXICO AND THEN INLAND ACROSS MEXICO MUCH MORE
QUICKLY. IT THEN PUSHES A COLD FRONT ALL THE WAY THROUGH SOUTH
TEXAS...WHICH DOESNT HAPPEN TOO OFTEN THIS TIME OF YEAR. SO BOTH
OPTIONS FOR GUIDANCE ARE ON EXTREME ENDS...SO FOR NOW...GOING PRETTY
NEUTRAL. THINK RAIN CHANCES INCREASE REGARDLESS...AS THE RIDGE
WEAKENS. TEMPS SHOULD ALSO DECREASE A BIT AT LEAST...MAYBE
MORE...WITH MORE CLOUD COVER/RAIN...AND COOLER TEMPS OFF THE
SURFACE. PLENTY OF TIME FOR THINGS TO FALL INTO PLACE AND THIS
FORECAST WILL /HOPEFULLY/ ONLY GET MORE CLEAR AS WE GO.

[perk]

The 18Z GFS may raise a few eyebrows for SE Texas.

[sambucol]

The 18Z GFS may raise a few eyebrows for SE Texas.

Why?

[perk]

The 18Z GFS may raise a few eyebrows for SE Texas.

Why?

Check the 18Z GFS run, i'm not saying SE Texas will get a big bad storm,but we could see some rain if it's right.

[sambucol]

Got a link to the run?

[srainhoutx]

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[srainhoutx]

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[sambucol]

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Is it reactivated now? I'm getting confused

[srainhoutx]

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Is it reactivated now? I'm getting confused

When the HPC update came out earlier it was almost a given that they wanted to run the Hurricane models on it. That was why I mentioned it in the August thread...

[srainhoutx]

Here are the thoughts from NWS Texas Offices:

Brownsville:

.LONG TERM /FRIDAY THROUGH TUESDAY/...PATTERN CHANGE ON THE
HORIZON AS THE WEAK RIDGING ALOFT GETS BROKEN DOWN OVER THE
WEEKEND. TEMPERATURES FRIDAY AND SATURDAY REMAIN HIGH AS
SUBSIDENCE CONTINUES AND KEEPS DRY AIR CONTAINED IN THE REGION.
NEXT SYSTEM IS RELATED TO THE TROPICAL WAVE THAT WAS TROPICAL
DEPRESSION SEVEN. THE REMNANT OPEN WAVE WILL DRIFT INTO THE
SOUTHERN GULF OVER THE WEEKEND AND BEGIN TO GET SCOOPED UP INTO
THE BROAD UPPER TROUGH DIGGING INTO THE EASTERN US. MODELS ARE
STILL DIFFERING ON WHERE THIS TROUGH AXIS FINALLY SETTLES...BUT IT
IS BECOMING MORE AND MORE LIKELY THAT IT WILL STALL ACROSS SOUTH
TEXAS OF ALONG THE IMMEDIATE GULF COAST. WHILE A TRUE TROPICAL
SYSTEM FORMING IS NOT LIKELY...THE VERY DEEP MOISTURE AND
INSTABILITY LOOK TO PROVIDE AMPLE SHOWER AND THUNDERSTORM ACTIVITY
FOR SOUTH TEXAS...LIKELY STARTING AS EARLY AS SUNDAY. HAVE GONE
AHEAD AND PUSHED UP POPS FOR MONDAY THROUGH WEDNESDAY
SLIGHTLY...OWING TO SOME CONTINUING INCONSISTENCY BETWEEN
MODELS...BUT EXPECT TO SEE SOME BETTER CHANCES FOR
RAIN...WHICHEVER MODEL IS USED.


Corpus Christi:

.LONG TERM (FRIDAY THROUGH WEDNESDAY)...COMPLEX FORECAST FOR THE
EXTENDED PERIOD AS A VARIETY OF SOLUTIONS ARE POSSIBLE. MAIN
FORECAST CHALLENGES THROUGH THE PERIOD WILL BE POPS LATE THIS
WEEKEND THROUGH EARLY NEXT WEEK AND MAX TEMPS EARLY NEXT WEEK.

STARTING WITH LATE THIS WEEK...HEIGHT AND WIND FIELDS SHOULD BOTH BE
LIGHT ENOUGH TO ALLOW FOR CONVECTION TO DEVELOP ALONG SEABREEZE
DURING THE AFTERNOON HOURS ON FRIDAY. BEST SURFACE CONVERGENCE AND
LOWEST HEIGHTS CURRENTLY PROG TO BE OVER INLAND NE ZONES AND IS
WHERE CHANCE POPS HAVE BEEN MAINTAINED. WEAKENING AND DIMINISHING
CONVECTION MAY APPROACH THE RIO GRANDE EARLY IN THE EVENING UNTIL
ATMOSPHERE STABILIZES FROM LOSS OF DIURNAL HEATING OCCURS.
ADDITIONAL ISOLATED CONVECTION SHOULD THEN DEVELOP LATE IN THE NIGHT
OVER THE MID TX COASTAL WATERS AS MARINE LAYER STRATIFIES TO
UNSTABLE. SIMILAR SET UP AS FRIDAY IS EXPECTED FOR SATURDAY
AFTERNOON AND EVENING WITH SLIGHT CHANCE TO CHANCE POPS ACROSS THE
AREA. FORECAST CONFIDENCE THEN LESSENS FOR THE REMAINDER OF THE
EXTENDED PERIOD.

THE REMNANTS OF TD HAVE BEEN MOVING ACROSS BELIZE AND INTO THE
YUCATAN THIS AFTERNOON. THE LOW AND MID LEVEL VORTICITY FROM THIS
CONVECTION IS PROG TO EMERGE OVER THE BAY OF CAMPECHE BY THIS
WEEKEND. AT THE SAME TIME AN UNSEASONABLY DEEP UPPER LEVEL TROUGH IS
PROG TO SWING INTO TEXAS WITH AN ASSOCIATED SURFACE FRONT PUSHING
SOUTH TO NEAR THE EWX/CRP CWA LINE BY EARLY MONDAY. WHILE THE UPPER
TROUGH IS DIGGING SOUTH IT WILL AID IN PULLING DEEP TROPICAL
MOISTURE UP FROM THE BAY OF CAMPECHE. SHOWER AND THUNDERSTORM
DEVELOPMENT SHOULD OCCUR OVER THE GULF WATERS TO THE EAST OF
TAMAULIPAS OVER THE WEEKEND. WITH A SURFACE FRONT DRIFTING SOUTH AND
EXTENDING EAST OVER THE WATERS AND WIND SHEAR PROG TO BE LIGHT TO
MODERATE...WE WILL HAVE TO MONITOR ANY PERSISTENT CONVECTION THAT
DEVELOPS OVER WATER. WITH THAT SAID...EACH GUIDANCE SUITE HAS A
DIFFERENT SOLUTION REGARDING SOUTH TEXAS WEATHER FOR EARLY NEXT
WEEK. GFS WANTS TO SPIN UP A TROPICAL SYSTEM IN THE SW GULF...ECMWF
WANTS TO STALL A FRONT ACROSS OUR AREA WITH DEEP TROPICAL MOISTURE
BEING ENTRAINED INTO THE REGION CONTINUOUSLY...AND THE CMC PLOWS A
FRONT SOUTH THROUGH THE AREA BRINGING FALL LIKE WX. CMC APPEARS TO
BE TOO STRONG AND TOO FAST WITH THE FRONT AND UPPER LEVEL TROUGH AND
HAS BEEN DISCOUNTED FOR NOW. OFFICIAL FORECAST LEANS CLOSER TO AN
ECMWF/GFS BLEND. FEEL THAT FRONT SHOULD MAKE IT INTO OUR REGION BY
EARLY NEXT WEEK WITH SHOWERS AND THUNDERSTORMS OCCURRING AT TIMES
DURING BOTH THE DAY AND NIGHTTIME HOURS. LOCALLY HEAVY RAINFALL MAY
ALSO OCCUR...BUT STILL TOO EARLY TO GET TOO SPECIFIC WITH PRECIP.
CAVEATS TO FORECAST...IF FRONT/TROUGH PUSH TOO FAR SOUTH THEN S TX
SHOULD RECEIVE A QUICK SHOT OF RAIN AND THEN DRY OUT. IF
FRONT/TROUGH REMAIN FARTHER TO THE NORTH THEN POTENTIAL FOR
SIGNIFICANT RAINFALL WILL INCREASE WITH POSSIBLE TROPICAL
DEVELOPMENT. ALL IN ALL...PROBABLY WOULD NOT BE A BAD IDEA TO STAY
UP TO DATE WITH THE LATEST WEATHER FORECAST OVER THE NEXT SEVERAL
DAYS.

WENT ABOVE ALL GUIDANCE FOR MAX TEMPS FRIDAY THROUGH SUNDAY AND THEN
CLOSE TO MEX NUMBERS FOR REST OF EXTENDED PERIOD DUE TO UNCERTAINTY.
MIN TEMPS REFLECT A MAV/MET/MEX BLEND WITH DEWPOINTS AND WIND
FORECAST A RAW CONSENSUS.



Ausin/San Antonio:

AS THIS SHORT WAVE DIGS FURTHER
SOUTH ON SUNDAY...HEIGHTS WILL WEAKEN CONSIDERABLY ALOFT AND WITH
MESOSCALE BOUNDARIES EXPECTED...ADDITIONAL SCATTERED SHOWERS AND
THUNDERSTORMS ARE EXPECTED. SEA-BREEZE ENHANCED ACTIVITY MAY ALSO
FIRE ALONG THE COASTAL PRAIRIES WHICH MAY INTERSECT EXISTING
BOUNDARIES AND ENHANCE FURTHER ACTIVITY LATE SUNDAY. WE`LL MAINTAIN
THAT UPPER LEVEL WEAKNESS IN THE RIDGE MONDAY AS A TROPICAL SYSTEM
HUGS THE NORTHEAST MEXICAN COASTLINE...CAUSING A SURGE OF SOUTHEAST
TROPICAL FLOW INTO THE REGION. EXPECT SCATTERED SHOWERS AND
THUNDERSTORMS TO DEVELOP MONDAY...MORE NUMEROUS ALONG THE COASTAL
PRAIRIES. HIGHS WILL ALSO LOWER MONDAY INTO THE MID TO UPPER 90S
MOST PLACES MONDAY WITH THE INCREASING TROPICAL MOISTURE. THE
12Z GFS SOLUTION BRINGS THE TROPICAL LOW INTO A COL AREA ALONG THE
NORTHEAST MEXICAN COAST...BECOMING NEARLY STATIONARY. THIS WILL
BRING DIURNALLY DRIVEN TROPICAL SHOWERS AND STORMS TO THE AREA
WITH ENHANCED PRECIPITATION AMOUNTS BY FRICTION ALONG THE COASTAL
PRAIRIES AND BY THE ESCARPMENT ALONG THE I-35 CORRIDOR BOTH MONDAY
AND TUESDAY. BY WEDNESDAY...THE MODELS HAVE THE TROPICAL SYSTEM
MOVING WEST INTO MEXICO WITH A CONTINUED CHANCE OF RAIN OVER SOUTH
CENTRAL TEXAS IN A BUOYANT TROPICAL AIRMASS.


Houston/Galveston:

REAL CHANGES ON THE WAY FOR FRIDAY AND ESPECIALLY THE REST OF THE
WEEKEND. COLD FRONT MOVING THROUGH THE PLAINS FORECAST BY GFS/ECM
INTO NE TX BY SATURDAY MORNING. POPS ON THE INCREASE AND WILL
SHADE THE FORECAST TOWARDS ECM-LIKE SOLUTIONS. BOTH MODELS WET BUT
DIFFER ON TIMING/LOCATION SO ALSO TENDED TO BROAD BRUSH POPS. FEEL
BEST CHANCE FOR RAINS IS LATE SATURDAY NIGHT INTO MONDAY. WEEKEND
RAIN TOTALS OF 1.00 TO 1.25 INCHES ON AVERAGE POSSIBLE WITH A FEW
LOCATIONS POSSIBLY RECEIVING MORE. ECMWF DOES PUSH FRONTAL SYSTEM
OFF THE COAST BEFORE STALLING. GFS KEEPS BOUNDARY/PCPN FURTHER
NORTH. ECM ALSO REMAINS WEAKER WITH ANY POSSIBLE LOW DEVELOPMENT
IN THE BAY OF CAMPECHE. GIVEN THE CLOSENESS TO SHORE OF ANY
DEVELOPMENT AS A HINDRANCE I KIND OF LIKE A 3 TO 1 BLEND OF ECM
TO GFS FOR THE FORECAST SUNDAY EVENING-TUESDAY WITH SCATTERED
PCPN CHANGES MAINLY OFFSHORE AND ALONG THE COASTAL AND NEAR
COASTAL COUNTIES. 04

[srainhoutx]

WEATHER RECONNAISSANCE FLIGHTS
CARCAH, NATIONAL HURRICANE CENTER, MIAMI, FL.
0930 AM EDT THU 16 AUGUST 2012
SUBJECT: TROPICAL CYCLONE PLAN OF THE DAY (TCPOD)
VALID 17/1100Z TO 18/1100Z AUGUST 2012
TCPOD NUMBER.....12-090

I. ATLANTIC REQUIREMENTS
1. REMNANTS OF TROPICAL DEPRESSION SEVEN
FLIGHT ONE --TEAL 73--
A. 17/2000Z
B. AFXXX 0207A INVEST
C. 17/1715Z
D. 20.8N 96.5W
E. 17/1930Z TO 17/2230Z
F. SFC TO 10,000 FT

2. OUTLOOK FOR SUCCEEDING DAY.....NEGATIVE.

[Portastorm]

No question that, just as the GFS showed earlier this week, the system is starting to spin up in the southern Bay of Campeche.

Looks like something is spinning up at 20 north/93.7 west.

[Portastorm]

NHC appears more and more interested ... up to 40% now!

---------------------
TROPICAL WEATHER OUTLOOK
NWS NATIONAL HURRICANE CENTER MIAMI FL
800 PM EDT THU AUG 16 2012

FOR THE NORTH ATLANTIC...CARIBBEAN SEA AND THE GULF OF MEXICO...

THE NATIONAL HURRICANE CENTER IS ISSUING ADVISORIES ON TROPICAL
STORM GORDON...LOCATED OVER THE CENTRAL ATLANTIC ABOUT 745 MILES
EAST-NORTHEAST OF BERMUDA.

SHOWER ACTIVITY...ASSOCIATED WITH THE REMNANTS OF TROPICAL
DEPRESSION SEVEN...IS SHOWING SOME SIGNS OF ORGANIZATION IN THE
EXTREME SOUTHWESTERN GULF OF MEXICO. ENVIRONMENTAL CONDITIONS
APPEAR CONDUCIVE FOR GRADUAL DEVELOPMENT DURING THE NEXT DAY
OR TWO...AND AN AIR FORCE RESERVE HURRICANE HUNTER AIRCRAFT IS
SCHEDULED TO INVESTIGATE THIS DISTURBANCE TOMORROW AFTERNOON...IF
NECESSARY. THIS SYSTEM HAS A MEDIUM CHANCE...40 PERCENT...OF
BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS AS IT MOVES
WEST-NORTHWESTWARD TO NORTHWESTWARD AROUND 10 MPH.

ELSEWHERE...TROPICAL CYCLONE FORMATION IS NOT EXPECTED DURING THE
NEXT 48 HOURS.

$$
FORECASTER KIMBERLAIN/AVILA

[Katdaddy]

Right on target Portastorm. Yep, becoming better organized the evening.